1. Technical Field
The present invention relates to examination methods, examination apparatuses, and examination programs, and in particular, to an examination method, an examination apparatus, and an examination program for performing examination related to an examining object by generating an X-ray tomographic image.
2. Related Art
An X-ray CT (Computed Tomography) is known as one example of a method of generating a tomographic image by an X-ray with a component mounting substrate as a target, and examining a joint state of a component side electrode and a substrate, an internal structure of a solder electrode, and the like using the generated image.
Japanese Unexamined Patent Publication No. 2006-292465 discloses one example of a technique related to the examination of a substrate using the X-ray CT.
With reference to FIG. 18A, Japanese Unexamined Patent Publication No. 2006-292465 discloses a technique of moving a bump on a substrate 920 to be examined to a field of view of an X-ray detector 950, and acquiring an X-ray image. The X-ray detector 950 is rotatable on a circumference of a radius R having an axis A extended in a vertical direction from a focus F of an X-ray generator 900 as a center. α is an inclination angle of the X-ray detector 950 with respect to the axis A. Here, the rotating operation of the X-ray detector 950 is performed, and the substrate 920 is moved within an X-Y plane so as to include the bump, which is the examination target, within the field of view of the X-ray detector 950 after the rotation. The field of view region FOV of the X-ray detector 950 is moved with the position in a Z-axis direction of the substrate 920 fixed, and the X-ray image is photographed by the X-ray detector 950 in a plurality of states of the field of view region FOV. The X-ray image is then photographed for a plurality of field of view regions FOV within the X-Y plane while changing the position in the Z-axis direction. A reconstruction calculation of a three-dimensional image is performed using the X-ray image for each of a plurality of field of view regions FOV obtained for a plurality of Z-axis directions.
In such photographing for the X-ray CT, the field of view region FOV of the X-ray detector 950 changes from FOV1 to FOV4 rotating with O, which is a correspondence point on the vertical direction of the focus F of the X-ray generator 900, as the center within the X-Y plane, as shown in FIG. 18B.
A method of generating a tomographic image of the substrate includes a method of generating a tomographic image of the substrate through tomosynthesis, that is, a method of generating a tomographic image of the substrate easier than the X-ray CT. For instance, Japanese Unexamined Patent Publication No. 2005-121633 discloses generating the tomographic image through such method. In Japanese Unexamined Patent Publication No. 2005-121633, an X-ray source 900 is arranged with an optical axis AX thereof facing upward in a perpendicular direction, an XY stage for supporting a substrate serving as an examining object 921, is arranged on the upper side thereof, and an XY stage for supporting a two-dimensional X-ray detector is further arranged on the upper side, with reference to FIG. 19. In FIG. 19, circular orbits R1, R2 are circular orbits having the optical axis AX (broken line) of the X-ray source 900 as a center. Each XY stage is moved along the circular orbits R1, R2 and stopped at every predetermined angle, and photographing is carried out. The images (P1 to P4) generated by each photographing are synthesized to generate the tomographic image.
As described in Japanese Unexamined Patent Publication No. 2005-121633, in the tomosynthesis photographing, each constructing point of the target plane is projected on the same coordinate of every image with a plane of a predetermined height as the target, and the relationship of the X-ray source, the X-ray detector, and the substrate in each photographing is adjusted so that each constructing point of the upper and lower planes is projected to different coordinates for every photographing. As a result, when each image is synthesized, the constructing points of the target plane are superimposed and become clear, but the constructing points of other planes become unclear. The tomographic image in which the noise is alleviated for the target plane thus can be generated.